This paper presents a set of design guidelines for the construction of complex, real-world problem-solving systems using a hybrid object-oriented deductive formalism. These guidelines address implementation issues in a multi-paradigm environment. Examples are provided in the context of a large-scale knowledge based system (KBS).>

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Interactive computer graphics can be an effective and efficient aid in the analysis/design cycle of engineering problems. The vistas of much engineering research and design can be expanded with the tools and methodology available with the introduction of an interactive computer graphics (ICG) system into an academic or industrial environment. Specific attention is given in this paper to new areas of application of ICG in civil engineering; guidelines for the planning of ICG systems; practical applications in bridge design and shipbuilding; and economic considerations involved in using ICG systems.

The modeling system described in this paper was developed in conjunction with computer program called STACRB that was developed in the CURT research project at the University of Pennsylvania. In essence, the static behavior of horizontally curved and straight aligned bridge structures.The modeling system communicates with the user through a problem oriented language. The commands in this language allow the user to define the parameters that characterize the structure, modify an already completed for a structure. The commands are entered in free format and are executed interpretively, thus allowing the user to communicate with the system in a conversational mode. The user may also enter the command on punched cards and execute the routine as a non-conversational batch job. The modeling system can be used to either control the analysis or operate independently from it. In the former case, the modeling system synthesizes the structure, then calls on the STACRB program to analyze it. When the analysis is completed, the control is returned to the modeling system to interpret the results of the analysis according to the commands supplied by the user. In the latter case, the results from the modeling procedure alone are punched onto cards which may subsequently be inputted to the analysis routine.The modeling system also includes facilities for graphical displays of components of the designed structure such as structure geometry and element discretization or results of analysis such as nodal deflections, reactions and element stresses. The displays may be produced either on the line printer for conversational purposes or on a CALCOMP plotter.The overall increased efficiency introduced by the modeling system in the analysis/design cycle of a bridge structure is quite significant.